Channels are known, in particular drainage channels with covers, in which the cover is set onto a bearing surface of the frame and is held there by screws, latches or similar devices. To do work within the channels, such as cleaning them, the cover must previously be raised and set down elsewhere. This requires a great deal of force and is also time-consuming.
A substantial disadvantage of this known arrangement consists on one hand in the expense involved in manufacturing and installing it, and on the other hand in the time taken to release and re-insert the screws.
Channel devices are also known in which hinges are provided, the leaves of which are connected to the frame and the cover, and which allow the cover to be pivoted to one side. A substantial disadvantage of this known channel device is that the cover cannot be detached from the frame, and hence cannot be removed. Another disadvantage associated with the use of hinges is that hinges require a great deal of maintenance. In particular when a channel is being used for the drainage of surface water, they will inevitably become dirty and corroded to an extent that their function is impaired, and the hinge region may even become fractured.
To avoid accidents, covers installed on streets or other places over which motor vehicles are driven should always be tilted in such a way that when struck by a vehicle, the cover closes by moving out of the tilted position in the direction in which the vehicle is travelling. If a known channel device is installed in the ground in such a way that tilting in this direction is impossible—that is, the arrangement has been wrongly installed—in order to satisfy this safety criterion the channel device must be taken out of the ground and put back correctly. Removal and re-installation of the channel device is extremely costly, in both money and time.
For installations in places with a steep longitudinal gradient, the hinges should be arranged such that it is possible to tilt the cover in the direction of the gradient. However, if the hinges are arranged in such a way that the cover can only be tilted against the direction of the gradient, the tilt angle of the cover will be reduced by an amount equal to the angle of the gradient. This means that the angle between the cover and the horizontal makes it more likely that cover will close in an uncontrolled manner, for instance as a result of a gust of wind or vibration. Uncontrolled closing of the cover presents a major risk of injury.
It is extremely disadvantageous when channel devices in which the hinges are so disposed that the cover cannot be tilted in the gradient direction must be laboriously and expensively dug up and installed anew, or else expensive devices must be provided to prevent uncontrolled closing of the cover.